Photocell Load Calculations

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fortunms

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I am looking at an installation of 3 - 150 watt High Pressure Sodium light fixtures on a 20 amp/120 volt circuit. I would like to use one common 1800 watt (ballast rated) photocell for all three lights. My question is: To determine the load on the photocell is it as simple as adding the total lamp wattage on the circuit or are there other factors to take into consideration.
 
Re: Photocell Load Calculations

You would also need to add to wattage for the HID Ballast for each fixture, that could be 25 watts each.
 
Re: Photocell Load Calculations

The answer to your question is yes, taking inot account whatever added lopad the ballasts might present as sugegsted by another poster.

You might also want to make sure that your photocell controller is suitable for the type of lights you want to use.
 
Re: Photocell Load Calculations

You can always install a 20 amp contactor and get rid of any load on photocell.Sometimes when I use HPS fixtures with photocells,tends to short last the photocell.
 
Re: Photocell Load Calculations

Thanks for all your help. Yes, I had thought about the use of a contactor but for right now will install a good quality photocell and see how it does. I am new to the web site and impressed with the content and professionalism of the forum.
 
Re: Photocell Load Calculations

Wouldn't you want to size it off the rated VA of the ballasts? And not the lamp wattage
 
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